Prof Samuel Stupp, of Northwestern University in Chicago, who led the study, believes the work could pave the way for the first effective treatment for spinal cord injuries. “I’m extremely excited and confident that this will help patients,” he said “We are going straight to the Food and Drug Administration (FDA) to start the process of getting this new therapy approved for use in human patients, who currently have very few treatment options.”
The therapy used a new class of smart materials to mimic the body’s extracellular matrix, the non-cellular component of all tissues that was once viewed as little more than an inert scaffold. However, there is growing evidence that the matrix plays a complex role in the body’s repair process through biochemical and biomechanical cues – and this is what Stupp and colleagues were aiming to replicate.
To do this they used a new class of materials called supramolecular polymers, made up of weakly bonded structural units that wiggle around and vibrate, allowing them to find and communicate with cellular receptors that are also constantly moving.
The therapy is based on designer molecules that mimic the natural environment of the spinal cord and send signals to trigger cells to repair and regenerate. The team behind the work hope to begin patient trials within two years.
There are an estimated 50,000 people in the UK living with a spinal cord injury and each year approximately 2,500 people are newly injured. There are currently no effective treatments to repair spinal cord damage.
These polymers can be dissolved in water and administered as a liquid injection, but on contact with living tissue instantly turn into a gel that remains in place at the site of injury.
“Cells immediately move into the spaces filled by water and get tangled in the nanofibers,” said Stupp. “Over the course of about two to three weeks these fibres are signalling the cells for repair.”
The latest paper, published in Science, described how mice with spinal injuries given a single injection of the synthetic matrix regained the ability to walk within three to four weeks of treatment. The study also found that the treatment caused severed extensions of neurons, known as axons, to regrow; a reduction in scar tissue, which can become a physical barrier to repair; the formation of new blood vessels and better survival of motor neurons. After the treatment has performed its repair function, it is biodegraded into nutrients for cells within 12 weeks and then disappears from the body altogether.
The advance comes after a number of high-profile studies into spinal cord injury in the past decade that are yet to translate into approved treatments for patients, including a study suggesting that electrical implants could help regeneration and another suggesting that injections of stem cells could be a promising treatment. Stupp expressed confidence that his team’s approach will, this time, deliver. “It does not involve the use of cells, it doesn’t involve the use of electricity and invasive devices or genes that can be dangerous,” he said. “Why this could be different from previous ideas is the therapy is very translatable. It’s a relatively simple molecule. That’s why we are so excited.”
The team plans to apply to the FDA next year for permission to conduct a human trial and hope that they could begin such a trial within two years.